Goofs

When Dan is taking a bath Mark/Luke brings in a tape and tape recorder with something for Dan to listen to and puts it on a shelf above the tub. While Dan and Mark/Luke are talking, Mark/Luke goes to leave and accidentally pulls on the electrical cord with his foot causing the tape recorder to fall towards the bathtub full of water which would supposedly electrocute Dan. Mark/Luke catches the tape recorder before it can fall into the bathtub full of water and Dan is saved. The problem is that the electrical cord is very clearly pulled completely out of the tape recorder and falls to the floor as soon as it begins to fall. When we change to a different camera view the cord magically has been reinserted into the socket of the tape recorder, which is only 12 volts as evidenced by the AC adapter in the plug in the wall which is shown in a camera shot when Mark/Luke pulls on the tape recorder cord with his foot causing it to fall.

In the wide-angle shot of Mark/Luke setting up the tape player on the shelf next to Dan's bathtub, we see him open the cassette-compartment lid. But then a moment later in a closeup shot where he inserts the cassette tape into the player, he opens the lid again.

When Mark/Luke climbs the electrical pole to cut the electrical power to the house he uses metal wire cutters with bare hands and it is pouring rain. This would cause him to be electrocuted under normal circumstances but he is unharmed.

The first part of the movie is set in 1974, yet there are 12 oz. Coca-Cola and Diet Coke bottles from the 1980s seen on one of the shelves at the grocery store. Furthermore, Diet Coke was not introduced until 1982.